Accelerometer gives wrong signals

[StathPol]

Thanks to all of you for your suggestions and comments.

The NI6361 card acquires voltage signals and supports single ended sensors. The accelerometer is one axis single ended sensor. The sensitivity of the accelerometer is 0.508 mV/g.

0.508 mV = 1g

0.000508 V = 1g

For 5000g, the voltage is 2.54 Volts

I have done a test using the modified scale today. I have changed the scale using MAX in the following:

Scale using MAX

Pre-scaled (Volts) --- Scaled (g)

-2.54 V                   =  -5000 g

0 V                         =    0 g

2.54 V                    =   5000 g

In the power supply conditioner, I used +/- V input range, and +5000 max. signal. Unfortunately, I do not have access to the sound and vibration suite.  The accelerations were high again and did not agree with both DIC and hand calculations.

Preston_Johnson: In the block diagram, I separated the arrays to put them in a bundle function so to separate them in the consumer loop in the waveform graph again. I just wanted to use the waveform graph in the consumer loop in order to not have any user interface actions in the producer loop.

Thanks,

Stath

[Henrik_Volkers]

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@StathPol wrote:

Thanks to all of you for your suggestions and comments.

The NI6361 card acquires voltage signals and supports single ended sensors. The accelerometer is one axis single ended sensor. The sensitivity of the accelerometer is 0.508 mV/g.

0.508 mV = 1g

0.000508 V = 1g

For 5000g, the voltage is 2.54 Volts

I have done a test using the modified scale today. I have changed the scale using MAX in the following:

Scale using MAX

Pre-scaled (Volts) --- Scaled (g)

-2.54 V                   =  -5000 g

0 V                         =    0 g

2.54 V                    =   5000 g

In the power supply conditioner, I used +/- V input range, and +5000 max. signal. Unfortunately, I do not have access to the sound and vibration suite.  The accelerations were high again and did not agree with both DIC and hand calculations.

Preston_Johnson: In the block diagram, I separated the arrays to put them in a bundle function so to separate them in the consumer loop in the waveform graph again. I just wanted to use the waveform graph in the consumer loop in order to not have any user interface actions in the producer loop.

Thanks,

Stath

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How is the conditioner gain setting?   If you enter a mV/Unit and range  in the conditioner you migth end up in a gain different of 1.

Have a look at the power spektrum of your signal and for a linear scale choose the sensitivity  at max power frequency ... 

Do you have a cal sheet (frequency response ) of your conditioner?

[StathPol]

Hi Henrik,

I have attached the conditioner certificate. The gain in the coditioner is automatically adjusted based on the sensitivity and signal inputs. Indeed, you are right. I enter the sensitivity as mV/g and the range in g and the gain is around 20.

Regards,

Stath

[StathPol]

I still do not get the right signals.

THe accelerometer has a sensitivty of 0.516 mV/g

0.000516 Volts for 1 g

I enter the following on the signal conditioning device:

Sensitivity of accelerometer: 0.516 mV/g

Range: 5000 g

Volts: +/- 10 Volts

On the LabVIEW, I specify signal range +/- 10 Volts

I hit the accelerometer and it gives 2 volts.Can you please help identifying what am I am doing wrong?

[billko]

I misread the question.  Sorry.

[StathPol]

Hi Bill, 

I re-posted the question

http://forums.ni.com/t5/LabVIEW/Accelerometer-voltage-signals-using-NI6361-module-PXI/td-p/3240420

[StathPol]

If the gain is automatically adjusted (range and sensitivity) to 3.83, do we have to divice the results by the gain??